1. Field of the Invention
The present invention relates to a mounting construction of a toner cartridge and an image forming apparatus to which the toner cartridge is attached.
2. Description of the Related Art
Conventionally, a toner cartridge is a consumable item and is attached to an image forming apparatus. The toner cartridge has one longitudinal end to which a rotary knob is attached and the other longitudinal end to which a cap is attached. After attaching the toner cartridge to the image forming apparatus, the knob is rotated so that the toner cartridge is opened to discharge the toner therein into the image forming apparatus. The image forming apparatus has a receiving section that receives the toner cartridge therein. The receiving section has a positioning rib that engages the longitudinal end of the toner cartridge for fastening the end portion, and a guide rib that engages the rotary knob.
When the toner cartridge is attached into the image forming apparatus, the operator holds the toner cartridge in such a way that the toner cartridge is oriented with its cap side positioned lower than the knob side. Then, the lower end of the toner cartridge is first inserted into the receiving section and then the higher end is inserted into the receiving section. Upon insertion of the entire toner cartridge into the receiving section, the toner cartridge extends horizontal and the rotary knob engages the guide rib. When the rotary knob is rotated, the toner cartridge is opened while at the same time the toner cartridge is locked to the receiving section.
With the aforementioned conventional structure through which the toner cartridge is attached to the receiving section, the toner cartridge is tilted immediately before it is attached to the receiving section. Therefore, the toner in the toner cartridge tends to move toward one longitudinal end of the toner chamber. As a result, the toner is not supplied uniformly across the longitudinal direction of the toner cartridge. This uneven distribution of toner across the length of the toner cartridge can cause poor print quality. If the toner cartridge is held horizontal and forcibly inserted into the receiving section, the longitudinal end of the toner cartridge interferes with, for example, the positioning rib.
Furthermore, when the toner cartridge is detached from the receiving section, the rotary knob is rotated in the opposite direction to a direction in which the knob is rotated when the toner cartridge is attached. Then, the toner cartridge is lifted. At this moment, one longitudinal end of the toner cartridge is caught by the positioning rib, which in turn causes the toner cartridge to tilt. Therefore, the image forming apparatus may be tilted forcibly, causing the toner to spill all over the surroundings within the apparatus.